Polycrystalline Cu-Al-Mn shape memory alloys (SMAs) with a low degree of order of the β (L2
1
) phase show excellent ductility and exhibit shape memory (SM) properties such as superelasticity, the ...one way memory effect and the two way memory effect based on martensitic transformation. These SM properties can be greatly enhanced by controlling microstructural factors such as grain size and texture by thermomechanical treatments. In the present paper, the SM properties of ductile Cu-Al-Mn based SMAs and microstructure control to obtain excellent SM characteristics are reviewed. Furthermore, an example of the application of Cu-Al-Mn based SMAs to a guidewire for medical use is also presented.
A point-location-based analysis of future climate change impacts on snow accumulation and melting processes was conducted over three study watersheds in Northern California during a 90-year future ...period by means of snow regime projections. The snow regime projections were obtained by means of a physically-based snow model with dynamically downscaled future climate projections. Then, atmospheric and snow-related variables, and their interrelations during the 21st century were investigated to reveal future climate change impacts on snow accumulation and melting processes. The analysis shows large reductions in snow water equivalent (SWE), snowfall to precipitation (S/P) ratio, and snowmelt through the 21st century. Timing of the peak of the SWE and snowmelt will also change in the future. Meanwhile, the analysis in this study shows that air temperature rise will affect, but will not dominate the future change in snowmelt over the study watersheds. This result implies the importance of considering atmospheric variables other than air temperature, such as precipitation, shortwave radiation, relative humidity, and wind speed even if these variables will not clearly change during the 21st century.
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•Climate change impacts on snow accumulation and melting processes were assessed.•Physically-based snow model with dynamically downscaling was used.•Relations among SWE, S/P ratio, snowmelt, air temperature, etc. were investigated.•The changes in snowmelt cannot be explained very well by a single variable.•The peak of snowmelt will happen earlier at the middle and higher elevations.
▶ NiMn
Z (
Z
=
Ga, Al, In, Sn, Sb) Heusler alloys are now very attractive because of their unique physical properties, such as, magnetic shape memory effect, magnetic field-induced phase transition, ...inverse magnetocaloric effect, magnetoresistance effect and the giant magnetothermal conductivity. ▶ In our previous investigations for the NiCoMnSn alloy, the behavior of the shape recovery due to the magnetic field induced reverse transformation has been reported. However, the detailed investigations on the magnetic properties such as metamagnetic behavior have not been made. ▶ In our present manuscript, we show the experimental results of the magnetic properties under the magnetic fields up to 12
T for NiCoMnSn alloy. We demonstrated the kinetic arresting behavior of the martensitic transformation under the high magnetic fields and thermodynamically discussed it. In addition, we analyzed the structure of the martensitic phase with a long period stacking structure and showed a lattice change between the before and the after the martensitic transformation. We believe that these results are high importance for understanding the interesting physical properties of the Ni-based ferromagnetic shape memory alloys and its applications.
High-field magnetic measurements were carried out in order to investigate behaviors of field-induced reverse martensitic transformation and kinetic arrest of NiCoMnSn metamagnetic shape memory alloy. In the thermomagnetization curves, it was confirmed that the reverse martensitic transformation temperature decreases 67
K by applying magnetic field of 5
T, while in the magnetic field cooling process under 5
T, martensitic transformation does not occur down to low temperatures. Equilibrium magnetic field, defined from the critical magnetic fields of the metamagnetic evidence in the magnetization curves, exhibits almost constant below about 100
K, suggesting that the entropy change becomes zero, which is considered to cause kinetic arrest behavior.
Editor’s summary In solid state materials, changes in the crystal lattice are often accompanied by changes in the electronic system. Whether the lattice or the electrons is the primary driver of a ...transition may, however, be difficult to ascertain. Noad et al. measured the Young’s modulus in the extremely clean material Sr2RuO4 as it underwent an electronic (Lifshitz) transition. The researchers found a large drop in the Young’s modulus at the transition, suggesting that conduction electrons drive a nonlinear elastic response in this material. —Jelena Stajic
The effects of ageing at 473–573
K on the hardness, microstructure and thermoelastic martensitic transformation in Cu–Al–Mn-based shape memory alloys were investigated. It was found that hardness was ...dramatically increased by ageing due to the formation of fine bainitic plates and that the volume fraction of the bainite phase with ageing time can be described by the Austin–Rickett equation. The martensitic transformation temperatures decreased with the formation of bainite plates, mainly due to the composition change of the β-matrix. Moreover, the growth of thermally induced martensite plates was disturbed by the existence of bainite plates. Consequently, the transformation intervals (
M
s–
M
f and
A
f–
A
s) and transformation hystereses (
A
f–
M
s and
A
s–
M
f) increased with the progress of bainitic transformation.
X-ray diffraction Rietveld structure refinement and mid- and far-infrared spectral studies have been done on Ga-for-Al and Ge-for-Si substituted synthetic clintonites (Cln), ...CaMg2(Al4-xGax)(Si1-yGey)O10(OH,OD)2 (x = 0.0-4.0, y = 0.0-1.0). Rietveld analyses indicate that there is complete solid-solution in both the (Al4-xGax)Si-, (Al4-xGax)Ge-clintonite series. With increasing Ga-for-Al, the mean tetrahedral bond-length, , and mean tetrahedral basal oxygen separation, <4Obas-Obas> increase, whereas the octahedral and interlayer parameters, the tetrahedral rotation angles (α), and the dimensional misfits (Δ) vary little. With increasing Ga-for-Al substitution in the Si-series the broad OH and OD stretching bands shift downward from 3607 to 3529 cm-1 and from 2671 to 2620 cm-1, respectively. For the Ge-series samples, the OH and OD stretching bands shift downward from 3610 to 3523 cm-1 and from 2667 to 2611 cm-1, respectively. According to the data of the curve fitting analysis, both the OH- and OD-stretching bands are modeled by at least three broad wider than 37 cm-1 of full-width at half height (FWHH) I bands (M1M2M2 = MgMgAl3+/MgMgGa3+) and a narrow (FWHH = 23-33 cm-1) and weak N band (M1M2M2 = MgMgMg) on the highest frequency side. In some samples, a very weak and broad V (one vacant M site) band at the lowest frequency region is observed. Tetrahedral Si-O, Al-O, and Ga-O stretching bands lie in fairly discrete regions, which are at 1030-830, 880-760, and 790-640 cm-1, respectively. However, the band regions for both the tetrahedral Al-O and Ge-O stretching as well as the Ge-O and Ga-O stretching bands closely overlap each other. In the 720-500 cm-1 region, Si-O-Al, Al-O-Al, Si-O-Ga, Al-O-Ge, Al-O-Ga, Ge-O-Ga, and Ga-O-Ga deformational bands (tetrahedral-chain bending and "breathing" modes) are observed to overlap strongly. Around 300 and 200 cm-1 one observes the Ca-Oinner and Ca-Oouter stretching bands, respectively, which show a slight downward frequency shift (approximately 7 cm-1 per Ga apfu) with Ga-for-Al substitution.
Abstract
A small-momentum-width muon beam, so-called ultra-slow muon beam, can be generated by laser ionization of muonium. To realize efficient ultra-slow muon generation, the Lyman-alpha and below ...360 nm coherent light are required to resonantly excite the muonium from the ground state to 2
p
and sequentially ionizes excited muonium to the unbound state. At the J-PARC MLF Ultra-Slow Muon beamline, we have successfully generated Lyman-alpha coherent light exceeding 10 μJ using an all-solid-state laser and high-efficiency vacuum ultraviolet light generation technologies. In this paper, we will describe the intense Lyman-alpha light source.
Abstract
Muonic atom X-ray Emission Spectroscopy (µ-XES) is a novel technique based on the detection of high-energy X-rays emitted after the interaction of a negative muon beam with matter. Thanks to ...the multi-elemental range, negligible self-absorption of the x-rays and the possibility of performing depth profile studies, the technique is a very powerful probe for the analysis of cultural heritage artefacts. By tuning the energy of the incident muon beam, indeed, it is possible to investigate the different layers that constitute a sample. In this work, we report preliminary results of the analysis on two fire-gilded surfaces, in which the data analysis is coupled with Monte Carlo-based simulation software. Here, to perform a depth profile characterization, the samples were analysed at different beam energies (or momentum). Each of the resulting x-ray spectra was then analysed and compared with the output of the simulations software and a remarkably good agreement was reached. The results of the work are promising and with this approach, it will be possible to enhance the capability offered by the technique, both in terms of data analysis and data interpretation.
The family Orobanchaceae includes many parasitic plant species. Parasitic plants invade host vascular tissues and form organs called haustoria, which are used to obtain water and nutrients. ...Haustorium formation is initiated by host-derived chemicals including quinones and flavonoids. Two types of quinone oxidoreductase (QR) are involved in signal transduction leading to haustorium formation; QR1 mediates single-electron transfers and QR2 mediates 2-electron transfers. In the facultative parasite Triphysaria versicolor, QR1 is involved in haustorium induction signaling, while this role is played by QR2 in the model plant Phtheirospermum japonicum. Our results suggest that there is functional diversification in haustorium signaling molecules among different species of the Orobanchaceae.
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